Checking on Earth's 'chimney'

Timothy B. Wheeler, The Baltimore Sun

For years, scientists have suspected that the warm waters of the western Pacific Ocean play a key role in shaping the Earth's climate. But satellite data provided only a partial picture of what's happening in this remote region of the globe.

Now, an international team of researchers, including several from Maryland, is engaged in an ambitious effort to quantify those natural processes, making dozens of flights in three aircraft from mid-January through February to track the gases and particles from the ocean as they rise into the upper atmosphere.

"This has interested scientists for many years because we know the atmosphere [there] acts like a huge chimney this time of year," Ross J. Salawitch, a professor of atmospheric chemistry at the University of Maryland, College Park, said from Guam.

The island, a U.S. military outpost and resort 3,300 miles west of Hawaii, is home base for the expedition. Salawitch is one of three principal investigators on the National Science Foundation-funded project; the other two are with the National Center for Atmospheric Research in Boulder, Colo., and with the University of Miami.

The region has long fascinated Salawitch, 53, whose research has focused on how human activity affects the Earth's atmosphere. While human influences have been closely scrutinized in recent decades, less is known about the natural sources and how the two interact, he said.

The waters south of Guam are ideal for that inquiry. They typically have the warmest open-ocean surface temperatures on Earth. That heat fuels the formation of storms with unusually thick, towering clouds, which push upward in a powerful convection current.

Three groups of scientists are studying the western Pacific chimney effect simultaneously, making dozens of flights to collect data. A team from Britain uses a plane flying as low as 50 feet above the waves to measure gases wafting up from the ocean through the troposphere, the lowest layer of the atmosphere.

Higher up, using a converted Gulfstream jet co-sponsored by the National Science Foundation and the National Center for Atmospheric Research, Salawitch and colleagues are tracking the chemicals' migration upward through the troposphere, from 25,000 to 50,000 feet above the ocean.

Finally, a band of NASA researchers is making a robotic, high-altitude survey up to 65,000 feet of what is reaching the stratosphere. They're remotely piloting an unmanned jet that can stay aloft for up to 24 hours at a time.

"We're going to find out what's here because it's largely unexplored," Salawitch said. "But certainly, as climate changes, as the Earth warms, so, too, will the sea surface warm. We expect, and models show, convection in this area will become more intense."

Of Guam, he said, "I don't think we could have picked a better place" as a research base. Temperatures climb into the 80s in daytime and low 70s at night. Typhoon season is basically over.

Among the questions under investigation is what role naturally produced chemicals play in thinning the ozone layer, which protects the Earth's surface from harmful ultraviolet radiation. The teams are sampling for chlorine, bromine and iodine compounds pulled from the ocean, on the theory that these natural compounds might be reacting with man-made ones in the stratosphere to hasten or aggravate the ozone depletion.

It's a big logistical undertaking, Salawitch said, as 88 researchers from various institutions and agencies are scheduled to visit Guam in shifts through February to work on the project. They're staying in local hotels, and those not flying monitor the data collection in rented laboratory space near the civilian airport where their plane is based. Salawitch said his team includes two graduate students and a research professor from College Park.

Another Marylander involved is Glenn M. Wolfe, a research scientist with the Joint Center for Earth Systems Technology, a collaboration between the University of Maryland, Baltimore County and NASA's Goddard Space Flight Center in Greenbelt.

Wolfe is part of a team focused on measuring formaldehyde, one of the highly reactive chemicals that migrates from the ocean's surface into the upper atmosphere. By flying near and downwind of storms, he said, scientists hope to measure how efficiently the gases are carried upward and how they alter the atmosphere's makeup.

"In a warmer climate, we expect convective activity to get stronger," Wolfe wrote in an email. "So, the results of this study will better prepare us to predict how the air will respond to a warmer world. ... This is a new frontier for atmospheric chemistry, and we are excited to see what's out there."

Salawitch, who grew up in Baltimore and graduated from Baltimore Polytechnic Institute in 1977, said scientists called for closer inspection of the tropical Pacific's effects on the atmosphere 15 years ago. With multiple flights to conduct intensive, coordinated sampling, he said he hopes the expedition can advance scientific understanding of the natural forces there and how they shape climate.

"It's very exciting to see the data for the first time," he said. "It's just amazing."